They’re each worth over a billion dollars, which earns them the status of “unicorn” in the venture capital world. According to the Wall Street Journal, there are 125 venture-backed private companies valued at $1 billion or more. Their total valuation: $500 billion.

There’s a ton of fixation around unicorns – and understandably so. The investors who back companies want to build billion dollar companies because it means they will become filthy-stinking rich when they buy out.

Except…it isn’t easy to find the next unicorn. Those 125 companies represent about 1% of all private companies. Not only is it rare but it’s getting harder and harder to spot the next unicorns.

Companies raise money at various stages during their development, called seed rounds. The number of early stage financing rounds has nearly tripled in the last few years, going from 1,500 in 2008 to over 4,000 by 2014. This means that the pool is becoming even more diluted. CB Insights crunched the numbers and came up with this nifty chart.

So, out of over 4,000 companies that raised money in 2014, only 6 have achieved billion dollar valuations. Imagine if it was your job in 2014 to find out which of those 4,000 companies would make the cut.

Generally, somewhere between 6-10 unicorns will be born every year. Out of all those, 1-3 will go on to become super-unicorns in a decade, worth more than $100 billion. One notable example in the past decade is Facebook.

Unicorns tend to fall pretty evenly between four major business groups: consumer e-commerce, consumer audience, SAAS (software as a service) and enterprise software. One caveat: enterprise-oriented unicorns tend to become worth more than the others.

There’s also this idea that startups that go on to be worth billions of dollars tend to have young 20-something technical founders who dropped out of Harvard. This actually isn’t true, and is more of an outlier than you would think.

The average age of unicorn founders is actually 34. Still young…but not as young as the now-25 year old founder of Snapchat, Evan Spiegel.

With all that said, you probably still want to know which startups might become the next unicorn. Here are 3 contenders:

1. Weebly

Weebly is a web hosting service with over 25 million users. The CEO David Rusenko says the company is cashflow positive and still have all of the $35 million it raised a year ago.

It’s most recent valuation placed it at just under half a billion dollars, so it has a ways to go…but the company looks to be in good health. They’re also backed by Sequoia Capital, an American venture capital firm with an excellent track record. Some of the companies it has funded include Airbnb, Apple, Google, Youtube, PayPal, Instagram, Oracle and Electronic Arts.

That’s quite the roster.

2. Remind

Remind is an app that helps teachers keep in touch with students and parents and its latest valuation puts in a similar space to Weebly. It sounds a bit niche but the company says they are already used by half the teachers in Georgia, and 40% of teachers in Texas. It’s completely free and is spreading like a virus in Resident Evil.

The company has $40 million in cash, and a user base of 1 million teachers communicating with 17 million parents and teachers. Education tech start-ups have a hard road ahead of them but people seem to be catching on.

3. Moovit

Another Sequoia Capital backed star. Valued at $450 million this start-up puts out an app that gives users real-time public transit information. Pretty useful for when you’re stuck outside wondering if your bus is ever going to arrive.

Other backers include companies like Nokia Growth Partners and transportation giants BMW and Keolis.

Moovit claims to have 15 million users and have raised $50 million to help them scale their business.

Fallen Unicorns

The trouble with just looking at which companies are currently approaching unicorn levels of valuation is that companies fall off the map ALL. THE. TIME.

In 2014, a company called Aereo was taking on all challengers. They aimed to deliver broadcast TV through the internet and grew like crazy, amassing 80,000 subscribers in short time. They also raised nearly $100 million, prompting investors to call it the killer of the TV industry.

Then, in June 2014, the Supreme Court ruled their service offerings to be illegal. By November they had filed for bankruptcy.

Starting a business is hard. Turning it into a unicorn is even harder. Every Uber and Dropbox stands on the corpses of thousands of dead companies before it.

Fab is another almost-there story. They saw huge success as an invite-only flash sales site. An item goes on sale for a short period of time and people flock to it before the timer runs down. In 2012, the site had 10 million members and by 2013, was actually valued at $1 billion. This was a unicorn!

The flash-sales niche died out pretty quickly though. In October of 2014 the company was reported to be burning $14 million every month and cut their staff from 750 to 185.

To complete their fall from unicorn grace, the company is in talks to be acquired by an Irish company for $15 million. So clearly, this was a case where speculation drove the valuation of the company to unrealistic proportions before coming crashing down to earth.

There are so many other stories. For every story that is reported on there are hundreds that never make the light of day.

Spotting the next unicorn is an art and a science and probably best left to the investment companies with proven success. The people at Sequoia Capital or First Round Capital have a proven track record of taking companies from birth to unicorn status and by following what they do one might be able to get an idea of where the next unicorn is hiding.